Multiphase fluid flows are common in pipes used in the transport of hydrocarbons for the petroleum industry. The current disclosure is directed to a method of using time of flight measurements to select a portion of the fluid that flows at a certain velocity. The velocity selection is accomplished by NMR spin-echo method. Difference in spin-lattice relaxation time T1 and spin-spin relaxation time T2 for different phases are used to differentiate the signal contribution from the different phases, thus making it possible to estimate the flow rate for each individual phase.